Changed the tags from Admire Vega (Umamusume) and Still in Love (Umamusume) to Copano Rickey (Umamusume) and Duramente (Umamusume). After a close look at the art, I concluded that these Umamusume are closer to Kitasan Black's in season 3 of the anime
The "Waaa!" at the end is "ぱぁぁぁぁ" in the original text, which is a sound effect for having a bright and happy look on one's face. This is either a creative difference or a mistranslation (the translator may have mistaken the ぱ for a は, which can be romanized as "wa" under certain conditions).